With the progress in the Global Positioning System (GPS) navigation device in recent years, the development of hand-held navigation device has gradually become matured. The hand-held navigation device can propose an optimal route when a user is driving toward a target location.
Generally, all the currently available navigation devices are able to provide different route planning functions, such as the fastest route planning function and the shortest route planning function. When the time factor is important to a user, the user would usually select the fastest route planning function. On the other hand, when the distance factor is important to the user, the user may select the shortest route planning function. When the fastest route planning function is selected, the navigation device would usually include freeways or viaducts, which are usually toll roads or toll bridges, in the navigation route. On the other hand, when the shortest route planning function is selected, the navigation device would usually include the toll-free surface roads and avoid all the toll roads.
However, the above two route planning functions fail to satisfy all the user's needs. For example, there are chances some part of a freeway on the navigation route is under construction or the user simply does not want to drive through a certain part of the freeway on the navigation route. Under these conditions, neither of the above two route planning functions is able to satisfy the user's need.